This invention relates to a device for measuring the amount or dosages of X-ray radiation to which a person is exposed during diagnostic X-ray examinations, or the like, as well as the overall X-ray radiation to which a person is exposed over a prolonged period of time. More particularly, this invention relates to a novel dosimeter carrier containing a plurality of removable radiation detectors for use in recording the respective amounts of radiation to which an individual is exposed during several different X-ray examinations, and a non-removable detector for measuring the overall background radiation to which the person is exposed over a prolonged period of time.
With the advent of sophisticated electronic equipment, the average person is exposed each year to more and more X-ray radiation. Also, with more interest in preventative medicine, the average individual is likely to be subjected to more diagnostic X-ray examinations than in earlier years. Even the modern-day home television set is capable of emitting dangerous levels of X-ray radiation. There is, therefore, a need for a relatively simple, compact, reliable means for measuring the quantity or intensity of X-ray radiation to which individuals are exposed during everyday living. Obviously this need is even greater in the case of those who are employed in or near the vicinity of X-ray emitting devices, such as for example medical personnel and supporting staff.
Heretofore efforts have been made to provide radiation detecting devices which can be used for determining the amount of radiation to which an individual has been exposed. U.S. Pat. No. 3,053,983, for example, discloses a film badge designed to be worn by personnel working in atmospheres where they are frequently exposed to hazardous X-ray radiation. The badge contains two strips of X-ray sensitive film, one of which after being used can be removed and developed to measure short term exposure to radiation (e.g. weekly), and the other of which can be removed only by destroying the badge, and is adapted to be used for long term monitoring, for example up to three months.
A major disadvantage of this construction is that it employs special X-ray sensitive film, the accuracy and sensitivity of which have extremely short life spans. The badge also requires careful packaging to avoid latent image fading due to atmospheric moisture. A further disadvantage of such a device is that the badge for housing the film strips is of rather complex construction to allow overlapping of the two film strips, and to provide filtered openings to expose selected portions of the film to background radiation.
U.S. Pat. No. 3,894,238 discloses a laminated dosimetric card (somewhat like an ID card) in which two or more crystal dosimeters or chips, as distinguished from the above-noted X-ray film sensors, are permanently sealed so that the card with all of its chips must be returned to be machine evaluated. Although such crystal dosimeters or chips have superior life spans as compared to film-type sensors, a disadvantage of this construction is that the chips are permanently fixed in the associated carrying card, and therefore cannot monitor individual X-ray exposures. The same is true of the card-type dosimeter taught by U.S. Pat. No. 3,652,854, wherein the chips also are sealed against removal from the card.
U.S. Pat. Nos. 3,612,870 and 3,638,017 disclose, respectively, carriers in which one or more radiation sensing film strips or thermoluminescent detectors (TLD's) are secured beneath removable covers. These constructions also have the disadvantage that their radiation sensing elements (chips or film strips, etc.) are secured in their respective carriers, and are designed to be removed only after they have been used, when it is necessary to measure the accumulated radiation detected by the respective elements.
While these prior art detectors may have certain advantages for special applications, they are nevertheless unsuitable for use in recording X-ray radiation which may be rather intense at selected intervals over a prolonged period of time, such as the typical medical or dental X-ray exposure. Typically such intervals comprise those instances in which a patent or individual is subjected to an X-ray examination for one reason or another. For satisfactory analysis of the radiation to which an individual has been exposed during such an examination, it is desirable to have available a separate, unused TLD which can be used to record in writing not only the date and time of exposure, but also the intensity and amount of X-ray radiation to which the individual is exposed during that particular examination. In addition, of course, it is most important to be able to record the overall or cumulative amount of X-ray radiation to which an individual is exposed over a prolonged period of time.
It is an object of this invention, therefore, to provide an improved wallet or compact-sized dosimeter device, which is particularly suitable for use in monitoring the amount of radiation an individual receives during one or more X-ray examinations conducted over a period of time, as well as for monitoring the overall amount of radiation to which the individual is exposed during the last-named period and for recording in writing pertinent information regarding the X-ray exposure.
A further object of this invention is to provide a novel dosimeter carrier, which contains a plurality of removable radiation sensing elements for use during X-ray examinations and the like and one additional sensing element which is not removable from the carrier, and which is designed to record the background X-ray radiation over a prolonged period of time.
Still another object of this invention is to provide a novel carrier of the type described which includes means for preventing accidental removal and reuse of the removable sensors once they have been used to measure radiation.
A more specific object of this invention is to provide a novel dosimeter carrier of the type described which includes means for shielding at least certain radiation sensors therein from background radiation.
It is an object also of this invention to provide a novel method of recording the amount of radiation to which an individual is exposed during X-ray examinations, as well as the cumulative background radiation to which the individual is exposed over a prolonged period of time.